Radiation therapy is a method of delaying or preventing the growth of a malignant tissue or extinguishing the malignant tissue by damaging or destroying a target tissue by using high-energy waves such as X-rays or gamma-rays or high-energy particles such as electron beams or proton beams. Recently, a radiation surgery method for treating without incision surgery by irradiating a large amount of radiation at one time has also been developed to replace a neurosurgical surgery method incising a skull.
It has recently been generalized such that about 60% or more of cancer patients may receive radiation therapy. Not only being used to treat a tumor by itself, radiation therapy may be used to reduce the size of a tumor to facilitate a surgical surgery or to destroy a malignant cell left after surgery, by being used together with other surgical surgeries for treating a local portion that fails to be removed by surgery or where surgery is difficult because a tumor is large and invasive.
Extracorporeal radiation therapy apparatuses for irradiating radiations from outside may be classified into low-energy X-ray therapy apparatuses, radioisotope therapy apparatuses, linear accelerators, particle accelerators, and the like according to the methods of generating high-energy particles or radiations.
The low-energy X-ray therapy apparatuses have been used to treat skin diseases or deep portions by using X-ray generating apparatuses, but they are rarely used nowadays.
The radioisotope therapy apparatuses use gamma-rays generated from radioisotopes such as cobalt-60 (Co-60). The radioisotope therapy apparatuses use gamma-rays having somewhat higher energy than the X-rays of the low-energy X-ray therapy apparatuses, but their use is gradually decreasing.
As apparatuses used as the standard of radiation therapy, the linear accelerators may output X-rays and electron beams, may transmit various energy, and may provide a high dose rate and beam-forming.
The particle accelerators have a structure for transferring neutron or proton particles accelerated by a cyclotron accelerator through a beam transfer pipe and emitting the same to a desired region through a nozzle, and may minimize a dose at a normal tissue and concentrate energy only on a deep tumor because they have a deeper Bragg's peak than the linear accelerators.
Recent medical radiation therapy apparatuses are developed in the form of mounting a radiation emitting head on a gantry having an arm or in the form of having a ring-type gantry, and a structure in which a radiation emitting head and a radiation detector face each other with a human body therebetween and rotate around the human body is mainly used. Information disclosed in this Background section was already known to the inventors before achieving the inventive concept or is technical information acquired in the process of achieving the inventive concept. Therefore, it may contain information that does not form the prior art that is already known to the public in this country.